Pharmaceutical Pollutants in Urban Rats Are Linked to Zoonotic Infection Risk

Pharmaceutical pollution is globally widespread and known to affect the biology and ecology of exposed wildlife. However, its effects on wildlife disease, including zoonotic (animal-to-human transmitted) infections, remains unclear. We examined the presence of 97 Active Pharmaceutical Ingredients (APIs) and their associations with zoonotic infections (Leptospira spp., Seoul orthohantavirus, Toxoplasma gondii, Capillaria spp., and Angiostrongylus spp.) in Rattus norvegicus and R. rattus rats, two globally distributed zoonotic reservoirs. We collected 152 rats from low-income urban communities in Salvador, Brazil, and detected APIs in 55.3% of the rats' brain tissues, providing novel evidence of pharmaceutical uptake in a wild, terrestrial mammal. Notably, Leptospira infection was 91% lower in rats containing the antibiotic azithromycin, while detection of antidepressant citalopram corresponded to a 3-fold increase in Capillaria infection risk. Our findings show that environmental APIs absorbed by rats are associated with variation in zoonotic infection risk, representing a previously unrecognized pathway through which pharmaceutical pollution may influence disease dynamics in cities worldwide.